Montana Dams
2,990 dams tracked by the National Inventory of Dams
Total Dams
2,990
High Hazard
188
6.3%
Poor / Unsatisfactory
132
Average Age
74 yrs
Hazard Classification
High188 (6.3%)
Significant193 (6.5%)
Low2,606 (87.2%)
Condition Assessment
Satisfactory113 (3.8%)
Fair44 (1.5%)
Poor / Unsatisfactory132 (4.4%)
Not Rated2,701 (90.3%)
Federal
278
State
151
Local
84
Private
2,466
Tallest Dams
- Yankee Doodle Tailings Dam570 ft
- Hungry Horse Dam564 ft
- Libby Dam422 ft
- Noxon Rapids260 ft
- Fort Peck Dam256 ft
High Hazard Dams
- Yankee Doodle Tailings DamHigh
- Hungry Horse DamHigh
- Libby DamHigh
- Noxon RapidsHigh
- Fort Peck DamHigh
Poor Condition Dams
All Dams in Montana
Showing 2026–2050 of 2,990
| Dam Name | Height (ft) | Year | Hazard | Condition |
|---|---|---|---|---|
| Obermayer Lake Lincoln County | 15 | 1950 | Low | Not Rated |
| O'Day #2 Cascade County | 60 | 1956 | Low | Not Rated |
| Odegard #2 Custer County | 15 | 1955 | Low | Not Rated |
| Offerdahl-Johnson Dam Phillips County | 17 | 1980 | Low | Not Rated |
| Ogdahl #3 Custer County | 21 | 1960 | Low | Not Rated |
| O'Haire Toole County | 23 | 1954 | Low | Not Rated |
| O'Halloran Park County | 23 | 1960 | Significant | Not Rated |
| O'Halloran #1 Park County | 23 | 1958 | Low | Not Rated |
| O'Henry Fallon County | 15 | 1930 | Low | Not Rated |
| Oh Henry'S Place Toole County | 27 | 1948 | Low | Not Rated |
| Oh No Dawson County | 20 | 1910 | Low | Not Rated |
| Ohs Phillips County | 14 | 1942 | Low | Not Rated |
| O J Rindal Fergus County | 25 | 1960 | Low | Not Rated |
| Okaga Lake Lincoln County | 15 | 1950 | Low | Not Rated |
| O Lane #1 Fergus County | 20 | 1975 | Low | Not Rated |
| Old Dibbler Ret. Dam Phillips County | 22 | 1912 | Low | Not Rated |
| Old Mcdonalds Pig Fergus County | 25 | 1960 | Low | Not Rated |
| Olie Toole County | 35 | 1956 | Significant | Not Rated |
| Olive Oil Blaine County | 22 | 1950 | Low | Not Rated |
| Oliver Detention Dam Carter County | 15 | 2003 | Low | Poor |
| Oliver, J. #1 Carter County | 14 | 1934 | Low | Not Rated |
| Ol John Garfield County | 18 | 1964 | Low | Not Rated |
| O'Lot O'Farmin' Liberty County | 37 | 1960 | Low | Not Rated |
| Olson #2 (Phillips) Phillips County | 10 | 1930 | Low | Not Rated |
| Olson (Garfield) Garfield County | 30 | 1960 | Low | Not Rated |
Data sourced from the National Inventory of Dams (NID). Hazard classification reflects potential consequences of failure, not the likelihood of failure.